Endometriosis is linked to a reduction in fertility before diagnosis of the disease, according to new research published on July 5.

Endometriosis is a chronic inflammatory condition that affects up to about 10 per cent of women of childbearing age. Tissue from the lining of the womb grows in other places, such as the ovarian and fallopian tubes.

Researchers from the Helsinki University Hospital in Finland found that the number of first live births in the period before the diagnosis of endometriosis was half that of women without the painful condition.

This was the case regardless of what form of endometriosis the women had: ovarian, peritoneal, deep endometriosis or other types.

In addition, the researchers found evidence that the number of babies women had before endometriosis was diagnosed was significantly reduced, compared to women who did not have endometriosis.

“Our findings suggest that doctors who see women suffering from painful menstruation and chronic pelvic pain, should keep in mind the possibility of endometriosis and treat them effectively,” said Professor Oskari Heikinheimo, at the varsity.

“Doctors should discuss with these women the possible effects on their fertility, in addition to the effects of their age, and the impairment of fertility should be minimised by offering relevant treatment for endometriosis without delay,” he added.

Typical symptoms of endometriosis include painful menstruation, pain in the pelvic area, difficult or painful sexual intercourse, and difficulty getting pregnant. Correct diagnosis is often delayed by around seven years.

Surgery has traditionally been the ‘gold standard’ for diagnosing the condition and classifying the type of endometriosis, although diagnosis by ultrasonographic findings or the symptoms alone is currently accepted.

Until now, there has been little information about the live birth rate among women with endometriosis, and little is known about the possible effects of different types of endometriosis on fertility, especially in the years before a diagnosis.

“Given the chronic nature and typical long delay in diagnosis of endometriosis, we wanted to find out if there were differences in first birth rates before diagnosis in a large group of women in the population,” said Prof. Heikinheimo.

In the study, published in the journal Human Reproduction, the team looked at 18,324 women in Finland, aged between 15 and 49 years, who had surgical verification of endometriosis between 1998 and 2012. They matched them with 35,793 women of similar age who did not have an endometriosis diagnosis.

A total of 7,363 women (40 per cent) with endometriosis and 23,718 women (66 per cent) without endometriosis delivered a live-born baby during the follow-up period of an average of 15.2 years.

The results showed that over the decades, an increasingly lower first-live birth rate was seen in women with endometriosis, compared to women without.